Vacuum relay

ABSTRACT

An improved high voltage vacuum relay is provided which includes internal shielding means which serves to prevent ionic discharge within the relay from the high voltage contacts thereof to its grounded magnetic actuating circuit, and which also serves to strengthen the bulb and to make the unit less susceptible to breakage.

United States Patent De Lucia 1 Oct. 10, 1972 [54] VACUUM RELAY2,966,569 12/1960 Jennings ..200/ 144 B [72] Inventor: gicltgu' E. DeLucia, Los Angeles, FOREIGN PATENTS OR APPLICATIONS a1 206,663 2/1968U.S.S.R ..200/144 B Ass1gnee= Torr Laboratories,- a Los 106,773 12/1963Netherlands ..,..200/144 B geles, Calif.

Primary Examiner-Harold Broome [22] Flled' 1970 Attorney-Jessup &Beecher [21] Appl. No.: 103,153

[57] ABSTRACT 52 us. Cl. ..335/201, 200/144 B An mp e high voltagevacuum relay is provided [51] Int. Cl. ..HOlh 9/32 which includesinternal Shielding means which Serves [58] Field of Search 5 /20 1,200/144 3 to prevent ionic discharge within the relay from the highvoltage contacts thereof to its grounded magnetic actuating circuit, andwhich also serves to strengthen [56] References Clted the bulb and tomake the unit less susceptible to UNlTED STATES PATENTS breakag3,154,655 10/ 1964 Hawkins ..200/144 B 2 Claims, 2 Drawing Figures A1zfii x/a- Z8 Z3; 3 if :521" axe 32 O h7g4 Va/Iage fflfll/d/l fllq#M-zaa0 56 (Ila/'32 2 1- 34 +2 aaza za I rama? 10 I 5 M 22 azmzPATENTEDum 10 I972 3 6 9 07 VACUUM RELAY BACKGROUND OF THE INVENTIONHigh voltage vacuum switches, or relays, are known to the art whichinclude relay switching contacts enclosed in an evacuated envelope. Sucha construction minimizes contact deterioration, and such relays may beoperated to switch high voltages over long operational periods withoutexcessive maintenance requirements.

However, during the switching cycle of a high voltage vacuum relay,arcing does occur between the contacts. The resulting arc consists ofionized metallic and gas particles, these ionized particles beingliberated from the relay contacts by the high temperature of the arc.The intensity of the ions so liberated is a function of the power beingswitched by the relay, and also of the gas embedded in the contacts andof the electron work function of the contacts.

In the prior art vacuum relay units, ionic discharge occurs between thehigh voltage contacts and the magnetic actuating members which areusually established at ground potential, the latter being includedwithin the envelope to increase the magnetic sensitivity of theactuating armature. Such an ionic discharge can become sufficiently highso as to create short circuits in the electrical circuitry associatedwith the relay. The ionic discharge is caused by the positive ionsreleased during the arcing action colliding with the few remaining gasmolecules still present within the evacuated envelope of the relay.

The vacuum relay of the present invention is constructed to incorporatean internal shield and metallic baffle, as will be described, so thatthe ions and electrons which are developed during the arcing of therelay contacts are not attracted and accelerated towards the groundedmagnetic actuating members, but are maintained in the upper portion ofthe envelope and neutralized when they collide with the shield andbaffle. With such a construction, no sustained discharge to the groundedmagnetic members is possible.

The structure of the present invention renders it possible for the relayto operate in conjunction with higher voltages than possible with priorart relays of the same size and electrical construction.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side section of a vacuumrelay constructed to incorporate the concepts of the present invention;and

FIG. 2 is a cross-sectional view of the relay of FIG. 1, taken along theline 2-2 of FIG. 1.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT The relay shown inFIGS. 1 and 2 includes, for example, an envelope formed of glass, orother vitreous or ceramic material. The envelope 10 is formed in knownmanner, and its open lower end is enclosed by a magnetic actuating unit12. The magnetic actuating unit 12 includes a central core 14 on whichan electric actuating coil 16 is wound. The coil is surrounded by amagnetic housing 18, and the magnetic circuit is completed by a lowercover plate 20, also formed of magnetic material. The magnetic actuatingunit 12 is normally maintained at ground potential, as indicated by theground symbol.

A magnetic armature 22 is hinged to the upper end of the magnetic unit12, and extends across the central core 16. A spring 24 normally biasesthe armature 22 to its illustrated inclined position. However, when theactuating coil 16 is energized, the armature is turned down to anessentially horizontal position.

An insulating rod 26 is mounted on the armature 22, and the rod extendsupwardly to a movable contact 28. The movable contact 28 is pivotallymounted, for example, in a first high voltage contact terminal pin 30,the terminal pin 30 extending through the wall of the envelope 10. Whenthe armature 22 is actuated in the manner described above, the movablecontact 28 is brought into selective contact with a second high voltageterminal pin 32 which, likewise, extends through the envelope 10.

The relay components, as thus far described, are know to the art. Asmentioned above, such a relay is capable of switching relatively highvoltages between the high voltage terminal pins 30 and 32 with a minimumof deterioration of the relay contacts. However, the voltages which maybe handled by such a prior art relay are limited, due to the fact thatthere is a tendency for an ionic discharge to occur between the highvoltage contacts 32 and the grounded magnetic members forming themagnetic unit 12 at the bottom of the relay.

Such a discharge is prevented in the construction of the presentinvention by providing a glass or ceramic shield 34 midway down theenvelope 10 and extending across the envelope, as shown in FIGS. 1 and2. The shield 34 may be integral with the envelope 10. A central opening36 is provided in the shield 34, and the insulating rod 26 extendsthrough the opening. In addition, a metallic baffle 40 is mounted on therod 26 directly under the opening 36. As mentioned above, the shield 34also adds strength to the envelope 10. The shield also serves to extendthe path on which a short circuiting metal film could be formed, therebymilitating against the formation of such a path.

With the illustrated construction, the electrostatic field within theenvelope 10 is minimized, so that there is no tendency for an ionicdischarge to occur between the high voltage contacts 28, 30, 32 and thegrounded magnetic unit 12. Instead, the ions are maintained in the upperpart of the envelope l0, and are neutralized as they contact the shield34 or the baffle 40. Therefore, the relay of the present invention bymeans of a simple expedient is capable of highly efficient operation,and of handling higher voltages than similar relays of the prior art.

Although a particular embodiment of the invention has been shown anddescribed, modifications may be made, and it is intended in thefollowing claims to cover all the modifications which fall within thespirit and scope of the invention.

What is claimed is:

1. In a vacuum relay which comprises an evacuated envelope formed ofvitreous material and having an open end, a magnetic actuating unitmounted at said open end of said envelope and enclosing said open end,and high voltage relay switching contacts mounted at relay switchingcontacts; and a baffle mounted on said rod adjacent said opening anddisposed on the side of said opening remote from said relay contacts,said baffle extending beyond the peripheral edge of said openmg.

2. The vacuum relay of claim 1, in which said baffle is composed of ametallic material.

1. In a vacuum relay which comprises an evacuated envelope formed ofvitreous material and having an open end, a magnetic actuating unitmounted at said open end of said envelope and enclosing said open end,and high voltage relay switching contacts mounted at the end of saidenvelope remote from said magnetic actuating unit; a vitreous shieldintegral with said envelope and extending across said envelope betweensaid magnetic actuating unit and said switching contacts to strengthensaid envelope and to inhibit ionic discharge within said envelopebetween said contacts and said magnetic unit, said vitreous shieldhaving an opening therein; an insulating rod extending from saidmagnetic actuating unit through said opening to said relay switchingcontacts; and a baffle mounted on said rod adjacent said opening anddisposed on the side of said opening remote from said relay contacts,said baffle extending beyond the peripheral edge of said opening.
 2. Thevacuum relay of claim 1, in which said baffle is composed of a metallicmaterial.